Getting to Dulles from Crystal City will be an expensive trip and time consuming trip. As noted above, I'd stick with DCA unless you want a*slightly* better shot at an upgrade. The 4:15 flight at IAD depending on day though usually sells out F seats before upgrades are processed. I'm a 75k, and lately the F seats are full days or more in advance. I've only seen the newer 320 a handful of times. Just hang at the hotel, or like another poster said, leave luggage and go walk the mall and see the Lincoln memorial. Take the metro a couple stops up and go to Arlington National Cemetery for the changing of the guard - it's a nice walk and a pretty moving experience.